Fly Ash- Its Impact on Yield and Trace Metal uptake by Crops Grown in Acid Soils

Abstract

Fly ash generated by captive power plants of Bokaro Steel Plant of SAIL was analysed for various properties and their role as plant nutrients. The yield of crops such as rice, wheat and soyabean and uptake of trace metals in fly ash amended soils by plants were assessed under green house conditions. Analysis of Fly ash reveal that it is moderately acidic (p/i 6.0). Exchangeable C& and Mgt* were major cations in the exchange complex. Total content of P, K, S and Fe in fly ash were high, while among nutrients in plant available forms, S (513 mg kg')and K (258 mg kg-') were high. Content ofDTPA extractable Ni was above toxic limit (29 mg kg 1). Experiments conducted in fly ash amended soils indicate increase in dry matter yield to soyabean, rice and wheat up to 16% (wlw) fly ash addition, Addition offly ash increased the concentration as well as uptake of different trace metals viz., Fe, Cu, Zn, Mn, Co, Pb and Ni by rice plant. Uptake ofNi by rice and wheat plants was reduced to some extent bysoil application of limealong with fly ash. In case of wheat,uptake of Fe and Ni increased considerably with fly ash additions to soil which is matter of concern from the point of trace metal contamination of soils. Uptake of Pb and Co by rice and wheat plants grown in fly ash amended soils was within the tolerance limits. Results indicate that fly ash can be usedfor soil amendment and as a secondary source of several essential plant nutrients and thereby help in increasing crop production. For mitigating the effectsof certain toxic metals infly ash, lime and or FYM application in soil along with fly ash is necessary.